Laminar starting plumes in high-Prandtl-number fluids
Laminar starting plumes in high-Prandtl-number fluids
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DOI：
10.1017/s0022112002003233
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发表时间：
2003-03
影响因子：
3.7
通讯作者：
É. Kaminski;C. Jaupart
中科院分区：
文献类型：
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作者：
É. Kaminski;C. Jaupart
对层流轴对称启动羽流进行了实验研究，考察了流动对普朗特数的依赖关系，重点研究了大普朗特数的影响。热羽流是由装满粘性油的玻璃水箱中的一个小电热器产生的。普朗特数在7-104的范围内被调查。在实验条件下，由于温差引起的粘度变化可以忽略不计。羽流以两种不同的方式上升，这是到源头的距离的函数。在短距离，由于粘性边界层的发展，羽流加速。在大于加热器大小约五倍的距离处，上升速度是恒定的，并随着普朗特数的增加而增加，正如理论预测的稳定羽流一样。在实验误差范围内，这个速度与稳定的羽流中心线速度成正比。
Experimental studies of laminar axisymmetric starting plumes are performed to investigate the dependence of the flow on the Prandtl number, focusing on large Prandtl numbers. Thermal plumes are generated by a small electric heater in a glass tank filled with viscous oils. Prandtl numbers in the range of 7–104 were investigated. Experimental conditions are such that viscosity variations due to temperature differences are negligible. Plumes ascend in two different regimes as a function of distance to source. At short distances, the plumes accelerate owing to the development of the viscous boundary layer. At distances larger than about five times the heater size, the ascent velocity is constant and increases as a function of the Prandtl number, as predicted by theory for steady plumes. This velocity is, within experimental error, proportional to the steady plume centreline velocity.